Annelids (ringed worms) range in size. The Giant Earthworms, of which Michrochaetus rappi is the largest. This worm’s average length is 54 inches (1.36 m) and largest recorded 22 ft (6.7 m) with a diameter of 0.8 inches (2 cm).
The smallest Annelid known to science is Chaetogaster annandalai which reaches a length of only 0.02 inches (0.05 cm)